I have fixed the problem now. In the last letter, with the Natural
class, I had not added
instance Num Natural where
(N x) - (N y) = N(x - y)
which the Ordinal class then in fact has one. Then it turns out that
it is merely the fact that "show" had some cases looking at the list
length that blocked its output. So there, one should probably have
some recursion that extracts elements one by one, without computing
list length, and adds a termination 2]" if the remaining list is empty.
So it seems possible to emulate Haskell list behavior with this
model, which is one thing I wanted to know.
Hans